As the size of electronic components decreases and their performance increases, compact notebook type personal computers for portability have become popular. Hence, many users use desktop type personal computers and notebook type personal computers at offices while they own a plurality of personal computers at home. As digital cameras and digital video cameras become popular, image data obtained by these cameras are managed by personal computers as the daily routine. Such image data has a large data volume, and the capacity of the hard disk or the like of a personal computer which stores the image data often becomes immediately insufficient.
In accordance with this situation, needs have arisen to be able to replace the hard disk of one personal computer easily so that it can be utilized in another personal computer. In particular, the capacity of the hard disk greatly increases year by year, and it is highly required to able to replace an old, small-capacity hard disk with a large-capacity hard disk. In order to cope with these requirements, a detachable hard disk (removable hard disk) that can be carried around easily and replaced easily has been proposed (for example, Japanese Patent Laid-Open Nos. 5-166102 and 2002-352546).
Progress and development in hard disks are remarkable, and the hard disks have been downsized and made to have lower profiles and higher performance. The specification sizes of the outer shapes of objects having the same storage capacity are becoming small day after day. Users particularly tend to prefer a compact removable hard disk because it is excellent in portability.
When downsizing of the removable hard disk progresses, however, the specification size of the outer shape of a new removable hard disk become largely different from that of an old one. Sometimes a cartridge having a storage medium cannot be physically mounted in and removed from a storage device main body which is provided outside or incorporated in a personal computer and designed in accordance with the old specification size of the outer shape. In this case, an adapter may be mounted to cope with different specification sizes of the outer shapes. This, however, makes the operation cumbersome. Moreover, when making electrical connection, the reliability may be degraded because the number of times the connection is made through the connector increases.